Apparatus for eliminating background noise

Abstract

An apparatus for eliminating background noise from a security marker authenticating system including a first sensor for capturing an image of a background of the security marker; a light source for illuminating the security marker; the first sensor or a second sensor or both captures a plurality images of the optical response of the security marker; a computer which averages the plurality of optical response images; the computer smoothes the background image; and the computer subtracts the smoothed background image from the average of the plurality of optical response images.

The invention claimed is: 
     
       1. An apparatus for eliminating background noise from a security marker authenticating system comprising:
 a sensor which captures an image of a background with a security marker; 
 a light source illuminating the security marker; 
 wherein the sensor captures a plurality images of an optical response of the security marker; 
 a computer which averages the plurality of optical response images; 
 wherein the computer smoothes the background image; and 
 wherein the computer subtracts the smoothed background image from the average of the plurality of optical response images. 
 
     
     
       2. The apparatus of  claim 1  comprising:
 wherein the computer calculates a score based on the number of pixels above a predetermined threshold; and 
 wherein the computer authenticates the security marker if the score meets predetermined requirements. 
 
     
     
       3. The apparatus of  claim 1  wherein the images are captured by a CCD or CMOS sensor. 
     
     
       4. The apparatus of  claim 1  wherein the background image are smoothed by applying a median filter on a pixel by pixel basis to the background image. 
     
     
       5. The apparatus of  claim 1  wherein the computer averages the plurality of optical response images by averaging the corresponding pixels of the plurality of images. 
     
     
       6. An apparatus for eliminating background noise from a security marker authenticating system comprising:
 a sensor which captures a plurality of image of a background with a security marker; 
 a computer which averages the background images; 
 a first light source illuminating the security marker; 
 wherein the sensor captures a plurality images of the optical response of the security marker; 
 wherein the computer averages the plurality of optical response images; 
 wherein the computer smoothes the averaged background image; and 
 wherein the computer subtracts the smoothed background image from the average of the plurality of optical response images. 
 
     
     
       7. The apparatus of  claim 1  wherein the computer averages the plurality of optical response images by calculating a resulting image wherein each pixel value is an average of the corresponding pixel values of the plurality of images.